1. Field of the Invention
The present invention generally relates to power converters. Specifically, the present invention relates to power converters operating in flyback mode and more specifically those that maintain high efficiency despite a wide range of line and load variations, have very low idle power consumption, and are low cost. Wherein, the ratio of high line to low line can be greater than 3 to 1.
2. Description of the Prior Art
Prior art embodiments customarily use DCM (Discontinuous Conduction Mode) operation for low power and CCM (Continuous Conduction Mode) operation for medium power conversion for wide range input AC to DC adapters. Employing purely CCM operation inherently produces high switching losses at high line whereas DCM operation for low power produces undesirably high conduction losses at low line input voltages. DCM operation allows for the minimization of the transformer size but increases conduction losses whereas CCM operation increases the transformer size requirement and switching losses.